S. Vanhatalo et S. Soinila, NADPH-DIAPHORASE ACTIVITY AND ITS COLOCALIZATION WITH TRANSMITTERS AND NEUROPEPTIDES IN THE POSTGANGLIONIC NEURONS THE RAT SUPERIOR CERVICAL-GANGLION, Brain research, 652(1), 1994, pp. 107-112
NADPH-diaphorase activity (NADPH-DA), a marker of neural nitric oxide
synthase, was found in many postganglionic nerve cell bodies in the ad
ult rat superior cervical ganglion (SCG) after colchicine treatment, p
ostganglionic nerve trunk ligation or ganglion culture. NADPH-DA coloc
alized with immunoreactivity to tyrosine hydroxylase (TH), serotonin,
vasoactive intestinal peptide (VIP), neuropeptide Y (NPY), methionine-
enkephalin and somatostatin. Almost all cells showing NADPH-DA were TH
-immunoreactive, although several TH-immunoreactive cells lacked NADPH
-DA. While suggesting that nitric oxide has an important role in the n
euronal modulation in the synaptic transmission in the rat SCG, our re
sults point out that nitric oxide synthesis is confined to a subpopula
tion of ganglion neurons. Our findings confirm the idea that the super
ior cervical ganglion consists of several subpopulations in which nora
drenaline is colocalized with other transmitter or neuropeptide. Only
about one-fourth of serotonin-immunoreactive neurons contained NADPH-D
A. Similarly, the neuropeptides studied showed only partial colocaliza
tion with NADPH-DA. Our results thus suggest that nitric oxide is not
associated with any particular transmitter or peptide.